1. Field of the Invention
The present invention relates to an earphone, and more particularly to a physiological function detecting earphone and a detecting method thereof.
2. The Related Art
The autonomic nervous system (ANS) is the part of the peripheral nervous system that acts as a control system, functioning largely below the level of consciousness, and controls visceral functions. The ANS affects heart rate, blood pressure, mood changes, life stress and so on. Therefore, if a person can early detect his autonomic nervous variation, personal health can be paid attention as early as possible to prevent individual physiological or psychological disease. Heart rate variability (HRV) is commonly used to show the ANS of variation in the time interval between heartbeats. Methods used to detect beats include: ECG, blood pressure, ballistocardiograms and the pulse wave signal derived from the photoplethysmography (PPG).
A traditional physiological function detecting earphone for detecting the heart rate variability (HRV) includes an earphone body, a light source and a light sensor. The earphone body has an earplug made of pervious to light material. In use, the earplug of the earphone body is inserted into the ear canal of a participant, then light emitted by the light source penetrates through the earplug and is reflected by the wall of the ear canal, and last the light sensor senses the reflected light changes in a period of time to get photoplethysmography (PPG) signals so as to detect the HRV.
However, manufacturing material of the earplug has an effect on transmittance of light through the earplug. Furthermore, the earphone is apt to move in the ear canal along with the shaking of the participant, so that will easily cause an interspace between the earplug and the wall of the ear canal. As a result, the light outside the ear canal can go into the ear canal through the interspace so that will affect the PPG signals got by the light sensor and ultimately affect the accuracy of the HRV.
Therefore, a physiological function detecting earphone capable of overcoming the abovementioned problems is required.